While Miley Cyrus mourns the death of her puppy, her fiancé Liam Hemsworth got himself into a little hot water. TMZ caught Hemsworth getting into a physical altercation with a stranger Sunday morning in Philadelphia.More celebs behaving badly: See some child stars gone badOn the tape, Hemsworth is seen punching a man in the face as he clings to the actor's leg. The incident began when Hemsworth and his friend thought the victim had thrown a rock them while leaving a bar. However, TMZ reports that no witnesses saw a rock get thrown.Cops arrived immediately afterwards, but no arrests were made. As of now, no charges against Hemsworth have been filed.